A very long, straight solenoid with a cross-sectional area of
2.24 cm^2 is wound with 85.2 turns of wire per centimeter. Starting
at t = 0, the current in the solenoid is increasing
according to i(t)= ( 0.180 A/s^2 )t^2. A
secondary winding of 5 turns encircles the solenoid at its center,
such that the secondary winding has the same cross-sectional area
as the solenoid.
What is the magnitude of the emf induced in the secondary
winding at the instant that the current in the solenoid is 3.2 A
?